Subido por Henry Centeno


15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
Using Elevator System Modelling and
Simulation for Integrated Learning in
Mechatronics Engineering
Lutfi Al-Sharif1, Tarek A. Tutunji 2, Dana Ragab2, and Range Kayfi2
Mechatronics Engineering Department, The University of Jordan, Amman 11942, Jordan
Mechatronics Engineering Department, Philadelphia University, Amman 19392, Jordan
Corresponding e-mail: [email protected]
Abstract - Elevator systems offer ideal platforms for
Mechatronics engineering education. Particularly, they
offer an excellent opportunity for integrating the
various mechatronics engineering disciplines, such as:
electrical motors and actuators, power electronics and
drives, control systems, system dynamics and
kinematicsAlthough elevator systems have been used as
learning platforms in engineeringeducation, the use of
elevator modelling and simulation for a well-structured
designprocess that includes analysis and synthesis is of
interest. Furthermore, documenting such work can help
mechatronics educators in using these models for their
case studies in different courses.
Simulink/SimPowerSystems based platform that was
built at Philadelphia University in order to allow
students to practice and understand the principles of
power electronics, drives systems, electrical machines
and control system design by modelling real life elevator
systems and running them. The learning outcomes
achieved by the projects include enabling the students
to model real life electromechanical systems, tune a PID
controller that controls the speed of the elevator system,
and design suitable power electronic drives to control
the used motor.
Keywords: mechatronics; education integration;
power electronics; electrical machines; simulation;
Matlab; Simulink; SimPowerSystems.
The main criticism of conventional engineering
education is twofold: the pure theoretical nature of
the study material and the compartmentalisation of
the different courses. Adding a practical hands-on
dimension to the study material and integrating the
different modules is considered a great enhancement
to any engineering degree programme.
Final year graduation projects and capstone
courses offer the student the opportunity to gain
practical experience in designing and building of
978-1-4799-3029-6/14/$31.00 ©2014 IEEE
systems and of integrating the different courses
studied during the undergraduate degree ([1], [2]).
Elevators are vertical transportation systems
that use motors and power electronics for mechanical
movements.Various pieces of research have been
published on the mechanical modelling of elevators,
a good example of which can be found in [12].
Elevator systems havebeen used as learning
platforms in many engineering courses but usually
only in programming the controllers [7]. A good
example on using a space elevator model to teach
power electronics can be found in [8]. However,
work that emphasize components’ selection, modules
interactions, and system design using the modelling
and simulation are very rare.
The elevator simulation model described in
this paper was built at the Philadelphia University
during the academic year 2013/2014. One of its
purposes was to integrate the three modules of:
Power Electronics and Drive Systems, Electrical
Machines and Automatic Control systems. The
intention is to enhance and expand the scope of the
model and use it in the future as a systematic tool
within the teaching of these modules. This paper
provides an overview of the model and provides
some insight into the rationale for developing such a
The use of Simulink as an engineering
modelling tool has been discussed in a number of
references ([3], [4], [5]). This paper emphasises the
use of Simulink as an educational tool for a specific
case study
Section 2 lists the modules linked to
theelevator model. It also highlights the learning
benefits to the students. Section 3 specifies the main
objectives and learning outcomes. Section 4 describes
various sub-blocks of the model and the function of
each block. Some results extracted from the model
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
are shown in section 5. Conclusions are drawn in
section 6.
The developed elevator model offers the students
hands on experience in a number of different
disciplines. It also allows them to cross reference the
different disciplines and understand the interrelationships among them.
The model presented in this paper is linked (but
not limited) to the following modules that are
standard components of most under-graduate
mechatronic engineering degrees:
Electrical machines and actuators.
Power electronics and drive systems.
Modeling and simulation.
Control system design.
Due to the practical nature of Simulink, it offers a
hands-on platform that allows the student to build
engineering systems, run them and then observe the
performance of the system.
They can then
troubleshoot problems in the system, improve the
performance and fine tune the settings of the
system.All of which are considered essential
elements in a successful design process.
It also provides them with the practical
understanding of inter-relationships among the
different disciplines. For example, studentswill use a
power electronics drive to actuate an electrical motor,
and can then find the system dynamics of the overall
system and tune the close loop controller to meet
certain system performance requirements (in the
transient phase and in the steady state phase).
The students are also forced to deal with and
solve practical problems that are not usually
addressed in the classical way of instruction, when
courses are taught separately. For example, students
have to introduce a saturation block into the
controller in order to represent the fact that the power
source feeding the dc motor has a finite voltage level
and that the motor has a maximum torque
specification. Another example, students must use a
double bridge driving the dc motor in order to
achieve driving and braking as needed.
skills required for mechatronic system design. The
following are the three main objectives of the
described project:
The motor, power drive, and power mechanism
selection are an integral part of mechatronics system
design [2].
This section describes the simulation model used in
detail. A block diagram of the whole model is shown
inFigure 1. Figure 2 shows the SIMULINK model of
the system. It follows a modular approach to building
the model. This allows the student to adopt a
modular based approach to model building and
practice the engineering principle of piecewise
building and stepwise refinement [6]. The students
can work in different teams, where each team
member can independently work (in parallel) on one
module, while still liaising with other members of the
team on the overall design of the model. This
approach teaches the students to follow the
synergistic design approach often implemented when
dealing with mechatronic systems.
The model comprises the following four main
modules: Controller, electrical drive, DC motor and
mechanical system.
The Controller block. This is the
Proportional-Integral (PI) block that
contains the PI parameters and the signal
pre-processing. This is directly linked to a
course inautomatic control. Students learn
the effect of varying the PI parameters and
observe their result to the elevator speed
behaviour. Students can then analyse the
transient and steady-state responses on the
elevator system. In order to get better
insight, theinternal structure of this block is
also provided to the students as shown
inFigure 3.The use of the saturation block is
used to demonstrate the practical issues of
voltage/power limitations to the students.
The Electrical Drive block that contains the
double six-pulse-controlled-rectifier bridges
The main goal of the elevator modelling and
simulation project is to teach the students essential
To equip the students with skills to model
real life electromechanical systems.
To enable the students to design closed
control systems, such as PID, for
electromechanical systems.
To enable the students to select suitable
actuators and power converters for elevator
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
used for driving and braking the DC motor
and the firing pulses generators. This is
very closely linked to a course on power
electronics and drive systems. The internal
structure of this block is shownFigure 4.
Due to the complexity of this block it is
further subdivided into three blocks: firing
pulses generator, signal processing and the
rectifier bridges.
Figure 5 shows the
rectifier block. The other two blocks are not
shown here because of space limitation.
The DC-Motor block which contains the
model of the dc motor used as the hoisting
motor and the processing necessary to
extract the torque from the motor and
feedthe actual speed. This is closely linked
to a course on electrical machines and
actuators. Theinternal structure of this
block is shown in Figure 6.During their
work, students calculate the required speedtorque characteristics and can then select the
appropriate motor from manufacturer’s data
sheets. When the selection process is
complete, students can enter the selected
motor parameters in the SIMULINK block
and verify the results. This motor selection
and verification skill is essential to the
mechatronic design process.
The Mechanical System block which
contains the details of the system inertia
(second moment of mass) referred to the low
speed shaft (LSS), the passenger mass, the
frictional model and the implementation of
the rotational equivalent of Newton’s second
law applied on the LSS. This is an ideal
application of a course on system dynamics.
Theinternal structure of this block is shown
inFigure 7.The students can experiment with
the mechanical system responses because
they have direct access to the linear and
rotational velocities and the linear
displacement. They can change the system
parameters (such as inertia, friction, and
radius), observe the curves, and analyse the
In SIMULINK, the Kinematics Generator block is
used to generate the velocity profile for a one-floor
journey of 4.5 m in this case, based on specified
values of rated velocity, rated acceleration and rated
jerk. This is closely linked to a course on dynamics.
The relationship between the velocity and
acceleration is highlighted using output scope plots
from SIMULINK. This relationship is further linked
to the mathematical foundations.
Figure 1: Simplified block diagram.
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
Figure 2: Simulink model of the elevator system.
Figure 3: Controller.
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
Figure 4: Electrical drive system.
Figure 5: Controlled 6 pulse three phase bridge rectifier.
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
Figure 6: Separately excited DC motor used as a hoist motor.
Figure 7: Mechanical load.
The reference speed is entered into the system as a
linear speed of the elevator car. The top rated speed
of the elevator is 1.6 m/s. The rated acceleration is 1
m/s2 and the rated jerk is 1 m/s3.
The kinematics generator is used to generate
a reference speed profile for a one floor journey of
4.5 m. The reference speed profile is shown inFigure
8. Superimposed on it is the actual linear elevator car
speed. The result is very good, but does not convey
the true performance of the system in terms of
stopping position accuracy. There is an error of
around 50 mm in the overall displacement, which
translates in the elevator into stopping inaccuracy.
One of the common mistakes that the
student makes when building the model is not to
include a braking rectifier bridge. This leads to
problems during the deceleration phase of the
elevator journey, as shown in Figure 9. It is clear
thatthe system is out of control during this phase, and
it is slowing down under the influence of friction
Furthermore, students can trace the signals
throughout the system in order to better understand
the controller actions, system dynamics, and
interaction between the sub-systems. The analysis of
the interaction between the blocks enforces the
concept of integration in mechatronic systems
Actual Speed
Figure 8: Actual and reference linear speeds for a one floor
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
Figure 9: Actual speed when no braking is present.
These plots are shown inFigures 10, 11, and 12. The
error, controller, drive, and motor signals are used to
help students understand the inputs and outputs of
each block. These are the outputs of themain blocks
shown in Figure 1 and Figure 2.
Figure 12: Drive output.
Figure 12 shows the signal representing the output of
the drive system. This is the signal that drives the
motor and has units of volts and provides braking as
well as driving. The fluctuations are due to the
rectifiers effect. Figure 13 shows the torque output of
the motor, which has fluctuation in it, and this is due
to the nature of the voltage signal applied to the
Figure 10: Error signal.
Figure 10 shows the error signal, which is the
difference in speed between the reference velocity
and the actual velocity. There is initially too much
fluctuation in its value, but it eventually settles down
to a smaller value. Figure 11 shows the controller
output. Note that is resembles the error signal
multiplied by the proportional gain in the PI
controller. The integral part is used to minimize the
steady state error
Figure 13: Motor torque output.
In addition, an integrator was added to the system
output in order to observe the displacement. The
results are shown in Figure 14. Students can then
compare the velocity (Figure 8) and the displacement
(Figure 14) and analyze the results. The target
displacement is 4.5m which is the vertical distance
between two levels.
Actual Displacement
Reference Displacement
Figure 11: Controller output.
Figure 14: Displacement output.
15th International Workshop on Research and Education in Mechatronics (REM), Elgouna, Egypt, September 9-11, 2014
There is a need within engineering education to offer
the students a more hands-on approach in studying
and integrating the various engineering modules.
This enhances the student’s understanding of the
various inter-relationships between the different
disciplines and enables him/her to tackle practical
types of problems not encountered within theoretical
study. The integrative approach to studying the
various modules counteracts the silo approach to
teaching the different modules..
An elevator modelling and simulation
platform has been built within Simulink/Matlab. It
consists of four main modules commonly used in
Mechatronics engineering: power electronics and
drives, electrical machines and actuators, automatic
control systems, kinematics and system dynamics.
The platform allows students to gain a deep
understanding of dynamic modelling of engineering
systems and dealing with practical problems in
control systems, such as the presence of saturation in
most actuators and output devices.
By adopting a modular approach in building
the platform, the students practice the principle of
piecewise building and stepwise refinement. It also
allows them to work as teams, with different team
members working on different modules within the
platform. Therefore, the students experience the
parallel design process and the interface
The platform can be further expanded to be
used for studying harmonics in electrical drive
systems, power factor calculation in non-linear loads,
the use of more advanced controllers (such as fuzzy
logic controllers) and the measurement and
modelling of electrical power consumption ([9], [10],
This research was carried out during the sabbatical
leave granted to Dr. Lutfi Al-Sharif by The
University of Jordan for the period from September
2013 to August 2014.
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